Several factors must be considered in order to optimize internal turning or boring. One factor is the limited space inside the workpiece which affects the design of the cutting tool in order to obtain an optimum balance between maximum strength/rigidity of the boring bar and minimum volume of the boring bar. Other important factors are chip flow and tool vibration both of which concern the position of the cutting edge in the limited space in workpiece. A known positioning solution involves the provision of a bar, which is substantially cylindrical in cross section ring bars having one or more longitudinal planar surfaces which are parallel to the longitudinal axis of the bar. The planar surfaces are often used to releasably secure the rotational position of the bar in the tool holder with at least one clamping device such as a clamping bolt. The clamping ends of the clamping bolts typically abut the planar surfaces of the boring bar. This design considerably effects and limits possible positioning of the boring bar in the tool holder and consequently effects shape and size of the cutting tool. Furthermore, changing boring bars typically involves screwing and unscrewing of more than clamping device. Thus, there is a need for improvements in these types of boring tools, and this is provided by the present invention.